Of course, this concept of a particle does not have any real correspondence in nature. The real world has extended bodies, formed by molecules, atoms of many types, which are formed by electrons, protons, and neutrons. Protons and neutrons are then formed by other basic structures known as quarks. Electrons are elementary by themselves. However, quarks and electrons cannot be described as classical particles, because eventually, this concept will not be sufficient to specify the way they exist. To understand if we are found in the domain of classical physics, we should learn if the above concept of a particle is, at least, approximately accurate to experiment. If this is the case, we may address the electron as a classical particle. Sometimes the classical particle is a sufficient concept.